├── 0x00 └── 0x00如何开始安卓逆向.md ├── LICENSE └── README.md /0x00/0x00如何开始安卓逆向.md: -------------------------------------------------------------------------------- 1 | # 如何开始安卓逆向 2 | 3 | > 不积跬步无以至千里，不积小流无以成江河 4 | 5 | ## 安卓逆向对抗历史碎碎念 6 | 7 | 在开始安卓逆向之前，需要对安卓的逆向对抗的历史有一些了解。 8 | 9 | 从普通用户的角度来看, 安卓从4.4版本开始，才算是一个勉强可用的操作系统，但从逆向的角度来看，安卓从7.0开始才算是开始在安全性方面有所建树。在安卓7.0之前各种*花活*可以玩的不亦乐乎。但是随着安卓生态的完善，对安卓APP的逆向分析难度是不断变大的。 10 | 11 | 在我看来，Android逆向的难度变大，主要原因如下: 12 | 1. Android 系统自身的安全策略，随着版本升级逐步完善。 13 | 2. 混淆和加壳等技术的成熟，使得免费版的加固方案也很好的安全性。 14 | 3. Android App的个人开发减少，大公司开发的App更有动力做安全加固。 15 | 16 | 17 | ## 从拿到一个Android安装包开始 18 | 19 | 当你从网上下载了一个Android安装包，你发现是一个`.apk`结尾的文件，你需要知道`.apk`文件是什么格式的，里面有什么内容，有哪些对抗的方式。 20 | 21 | ### apk文件是什么格式的 22 | > APK（全称：Android application package，Android应用程序包）是Android操作系统使用的一种应用程序包文件格式，用于分发和安装移动应用及中间件。 23 | 从逆向分析的角度来看，APK文件更像是一个压缩包，你可以把文件后缀改为.zip，然后使用解压软件打开。 24 | 25 | ### APK里面有什么内容 26 | 27 | 对于不同的开发模式和Android版本来说，APK文件里面内容是略有差异的，但是一般情况下，都有如下的内容 28 | - AndroidManifest.xml 安装包的核心配置文件，记录了包名、应用名、权限等配置。android低版本的时候就是xml的纯文本，高版本的安卓是 axml格式的 29 | - classes*.dex 可能会有一个到多个dex文件，包好了java或kotlin编译后的二进制文件，这个逆向分析的重点 30 | - assets文件夹， 保存了一些静态的文件，如果是uniapp开发应用，可能会有一些重要的js源码 31 | - lib文件夹 保存了不同平台的Linux平台的.so文件, 是标准的ELF格式的，一般是ARM架构的。重要反调式和加密函数一般会在.so文件中，也是逆向分析的重点 32 | - 其他文件，一些签名和配置文件等，对开发来说很重要，但不是逆向关注的重点。 33 | 34 | ### 逆向与对抗的方式 35 | 36 | #### 破坏压缩包格式来对抗逆向 37 | 38 | apk文件类似于一个压缩包，逆向分析软件是通过先解压然后在进行分析的， 这个时候对apk文件做一些细微的改动，如改动压缩包的标识符，加入一些乱码的字符，从而达到apk文件可正常安装，但是无法使用逆向分析工具来分析。看雪论坛的这篇文章有相关的介绍 39 | https://bbs.kanxue.com/thread-272045.htm 40 | 41 | 这种较为初级的对抗很多黑灰产的APP在使用，目的是为了逃避自动化的apk检测系统。对于逆向分析人员来说，使用binwalk提取文件或者使用`010 Editor`修复格式，然后提取文件分析即可。 42 | 43 | #### 代码层来对抗逆向 44 | 45 | dex文件 46 | 1. 把方法名称混淆成abcd无意义的字符，更恶心的混淆成火星文，分析难度加倍, 只能耐心硬上，无通用解决方案。 47 | 2. 加壳，分为一代二代三代壳，一代二代壳基本动态分析可解决，三代壳看运气了。 48 | 49 | so文件 50 | 1. 去掉符号表、混淆命名, 可通过函数签名解决部分, ida Pro和Ghidra都有类似的功能 51 | 2. 字符偏移，动态分析可解，难度较大 52 | 3. 反调试，动态分析可解，难度看运气 53 | 54 | 55 | 56 | ## 工具与技能 57 | 58 | ### 工具 59 | 静态分析工具有很多，但是目前最好用的就是 Jadx,对于.so文件的分析比较好用的就是 IDA PRO和 Ghidra 60 | 61 | 动态分析，一般使用Frida来hook。 62 | 63 | 抓包分析工具，我一般使用 Mitmproxy(支持的代理模式多，功能强大，可通过Python写插件非常方便） 64 | 65 | ### 技能 66 | 67 | 从编程语言来说，至少对JAVA/Kotlin/Python/C/JavaScript都要有所了解，并且熟悉一门编程语言。例如本人就比较熟悉Python，并且能在搜索引擎帮助下看懂和写其他几门语言 68 | 69 | 从安卓系统来说，要对安卓开发有所了解，并且需要会配置各种环境。 70 | 71 | 更重要的是善用搜索引擎，逆向和对抗时刻变化，动态平衡中。 72 | 73 | 74 | 75 | 未完待续！ 76 | 77 | 78 | 79 | 80 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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[如何开始逆向分析](0x00/0x00如何开始安卓逆向.md) 15 | 2. 逆向分析工具视频教程 16 | - [逆向分析工具Ghidra使用教程](https://www.bilibili.com/video/BV1524y1b7Ar/) 17 | 18 | 19 | 20 | ## 问题反馈 21 | 22 | 欢迎通过 issues 来提出问题和建议 23 | 24 | 欢迎通过 Pull request 来一起改进项目 25 | 26 | 不欢迎伸手党和外包邀约。 27 | 28 | 29 | ## 作者介绍 30 | 31 | 略 32 | 33 | ## 免责声明 34 | 35 | 本项目涉及的内容仅供学习使用，请勿用作其他用途。 --------------------------------------------------------------------------------